about FSK data question....

super

Dear all :
              In fsk close loop direct Frequency modulation ,
          1.  data rate is higher than loop BW  or lower than loop BW ?
          2.  And what's the relation between data rate and Loop BW ?
) Z" l4 I# W2 v0 N1 Q
           Because modulation from VCO , it's a high pass function for VCO vs PLL.
           If modulation frequency > BW , it will be supress by VCO vs PLL transfer function.
           It will be trace and fix it.  So modulation function is fail.
  g' a3 ~( F- l! b0 w( M0 q$ d             Is this concept is right ?
" x; }7 I. u# f$ e+ w7 U5 b                  
                    Thanks .

simenkid

1.data rate可以高於loop bandwidth, 也不可以.端看用什麼architecture
2.假使單純在multi-modulus或是由reference端做調制, data-rate高於loop bandwidth則勢必產生失真

直接由PLL Synthesizer調制提升FSK, FM, GMSK等固定波包調制之data rate
, w& X; s9 k0 U可選擇如pre-emphasis或two-point modulation(同時兼顧inband與outband,理論上無頻寬限制)的方式